Cubic Feet to Gallons: Formula & Conversion Chart

Cubic Feet to Gallons

Convert cubic feet to gallons by multiplying the cubic-foot volume by 7.48052 for US liquid gallons, or by 6.22884 for imperial gallons. One cubic foot equals 7.48052 US gallons, so a 10-cubic-foot volume holds 74.8 US gallons. The two conversion factors differ because the US gallon and the imperial gallon are different sizes.

Cubic feet measure the space an object or container occupies, while gallons measure liquid capacity, so this conversion answers how much water, fuel, or liquid a given space holds. The Cubic Feet Calculator computes a volume first, and this guide turns that volume into gallons with a formula, a chart, and worked examples. Run the same conversion live with the Cubic Feet to Gallons Converter.

The Cubic Feet to Gallons Formula

The formula is Gallons (US) = Cubic Feet × 7.48052. The factor 7.48052 is exact by definition, not an approximation. One US liquid gallon equals 231 cubic inches, and one cubic foot equals 1,728 cubic inches, so dividing 1,728 by 231 gives 7.48052 gallons per cubic foot.

For imperial gallons, the formula is Gallons (imperial) = Cubic Feet × 6.22884. The imperial gallon is defined as 4.54609 liters, and one cubic foot equals 28.3168 liters, so 28.3168 divided by 4.54609 gives 6.22884. Choose the factor that matches the gallon your country uses, because mixing the two produces a result off by about 20 percent.

How to Convert Cubic Feet to Gallons Step by Step

Convert cubic feet to gallons in 3 steps:

1. Confirm the volume is in cubic feet, converting from cubic inches by dividing by 1,728 if needed.
2. Choose the correct factor: 7.48052 for US gallons or 6.22884 for imperial gallons.
3. Multiply the cubic-foot volume by the chosen factor to get the gallon capacity.

For 15 cubic feet in US gallons, multiply 15 by 7.48052 to reach 112.2 gallons. The multiplication is the only calculation, so the accuracy of the result depends entirely on measuring the volume correctly in the first place. A volume measured in inches must be divided by 1,728 before this step, because the factor assumes cubic feet.

Cubic Feet to Gallons Conversion Chart

The chart below converts common cubic-foot volumes to both US and imperial gallons. Each US value multiplies by 7.48052, and each imperial value multiplies by 6.22884.

Cubic feet	US gallons	Imperial gallons
1	7.48	6.23
2	14.96	12.46
5	37.40	31.14
10	74.81	62.29
20	149.61	124.58
50	374.03	311.44
100	748.05	622.88

The chart scales linearly, so a value not listed can be found by combining rows: 25 cubic feet equals the 20-row plus the 5-row, or 149.61 plus 37.40, which is 187.01 US gallons.

Worked Example: Gallons in an Aquarium

A rectangular aquarium measures 4 feet long, 2 feet wide, and 2 feet deep. Find its capacity in US gallons.

1. Calculate the volume: 4 × 2 × 2 = 16 cubic feet.
2. Multiply by the US factor: 16 × 7.48052 = 119.69 US gallons.
3. Round for a practical figure: about 120 US gallons at full depth.

An aquarium is rarely filled to the exact top, so a fill line 2 inches below the rim reduces the depth used in the volume. Recomputing with a depth of 1.83 feet gives 4 × 2 × 1.83 = 14.64 cubic feet, or 109.5 US gallons. Measuring the filled volume, not the tank’s outer size, gives the honest water capacity, the same principle covered in the guide on how to calculate cubic feet of a refrigerator.

How to Convert Gallons Back to Cubic Feet

Reverse the conversion by dividing gallons by the same factor. Cubic Feet = US Gallons ÷ 7.48052. For 250 US gallons, divide 250 by 7.48052 to reach 33.42 cubic feet. This answers how much space a known volume of liquid needs, which matters when sizing a tank or a storage container.

For imperial gallons, divide by 6.22884 instead. A 250 imperial-gallon volume equals 250 divided by 6.22884, or 40.14 cubic feet. Keeping the same gallon type on both sides of the conversion is essential, because dividing US gallons by the imperial factor mixes two definitions and returns a wrong result.

Related Volume Conversions

Cubic feet convert to other liquid and volume units with a single factor each:

1. Cubic feet to liters: multiply by 28.3168.
2. Cubic feet to US quarts: multiply by 29.9221.
3. Cubic feet to cubic yards: divide by 27.

Liters are the metric partner of gallons, so a volume needed in both systems uses the Cubic Feet to Liters Converter alongside the Cubic Feet to Gallons Converter. A single measured cubic-foot volume feeds every one of these conversions without remeasuring.

Frequently Asked Questions

How many gallons are in a cubic foot?

One cubic foot holds 7.48052 US liquid gallons or 6.22884 imperial gallons. The US figure comes from the definitions: one US gallon equals 231 cubic inches, and one cubic foot equals 1,728 cubic inches, so 1,728 divided by 231 equals 7.48052. Multiply any cubic-foot volume by 7.48052 to get US gallons.

How do you convert cubic feet to gallons?

Multiply the number of cubic feet by 7.48052 for US gallons. For a 20-cubic-foot volume, multiply 20 by 7.48052 to get 149.6 US gallons. For imperial gallons, multiply by 6.22884 instead, which gives 124.6 imperial gallons for the same 20 cubic feet. The two results differ because the imperial gallon is larger than the US gallon.

What is the difference between US gallons and imperial gallons?

A US liquid gallon is 3.78541 liters, and an imperial gallon is 4.54609 liters, so the imperial gallon is about 20 percent larger. Because of that size difference, one cubic foot equals 7.48 US gallons but only 6.23 imperial gallons. Use US gallons in the United States and imperial gallons in the United Kingdom.

How many gallons of water are in a 10 cubic foot tank?

A 10-cubic-foot tank holds 74.8 US gallons of water. Multiply 10 cubic feet by 7.48052 to reach 74.8052 gallons. This assumes the tank is filled completely; a real tank filled to a lower line holds less, so multiply the filled volume in cubic feet, not the total tank size, for an accurate figure.

How do you convert gallons back to cubic feet?

Divide the number of US gallons by 7.48052 to get cubic feet. For 100 US gallons, divide 100 by 7.48052 to reach 13.37 cubic feet. This reverses the cubic-feet-to-gallons conversion, and it answers the common question of how much space a known volume of liquid will occupy.